How to Use Sparkfun COM-18356: Examples, Pinouts, and Specs

The Sparkfun COM-18356 is a versatile and compact USB to serial converter module designed to facilitate seamless communication between a computer and microcontroller or other serial devices. This module is based on the CH340C USB-to-serial chip, which ensures reliable data transfer and compatibility with a wide range of operating systems, including Windows, macOS, and Linux. Its small form factor and ease of use make it an essential tool for prototyping, debugging, and programming microcontroller-based projects.

• Programming and debugging microcontrollers such as Arduino, ESP8266, and ESP32.
• Establishing serial communication between a computer and embedded systems.
• Interfacing with serial devices like GPS modules, sensors, and displays.
• Prototyping and testing serial communication protocols.

The following table outlines the key technical details of the Sparkfun COM-18356 module:

The Sparkfun COM-18356 module features the following pins for interfacing:

1. Connect the Module to Your Computer: Use a USB Type-C cable to connect the COM-18356 module to your computer. Ensure that the necessary drivers for the CH340C chip are installed. These drivers are typically available on the Sparkfun website or can be downloaded from the manufacturer's site.

2. Configure the Voltage Level: Set the voltage level (3.3V or 5V) using the onboard jumper. Ensure the selected voltage matches the logic level of the device you are interfacing with.

3. Connect to Your Device:

   • Connect the TXD pin of the COM-18356 to the RX pin of your device.
   • Connect the RXD pin of the COM-18356 to the TX pin of your device.
   • Connect the GND pin of the COM-18356 to the ground of your device.
   • Optionally, connect the DTR pin to the reset pin of your microcontroller for programming purposes.

4. Open a Serial Terminal: Use a serial terminal program (e.g., Arduino IDE Serial Monitor, PuTTY, or CoolTerm) to communicate with your device. Select the appropriate COM port and baud rate.

• Driver Installation: Ensure that the CH340C driver is correctly installed on your computer. Without the driver, the module may not be recognized.
• Voltage Compatibility: Always verify the voltage level of your target device before connecting the module. Incorrect voltage settings can damage your device.
• Cable Quality: Use a high-quality USB Type-C cable to ensure reliable data transfer and power delivery.
• Avoid Crossed Connections: Double-check the TXD and RXD connections to avoid communication errors.

Below is an example of how to use the Sparkfun COM-18356 to communicate with an Arduino UNO:

• Connect TXD of COM-18356 to RX of Arduino UNO.
• Connect RXD of COM-18356 to TX of Arduino UNO.
• Connect GND of COM-18356 to GND of Arduino UNO.

// Example code to send and receive data via Sparkfun COM-18356
void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
  Serial.println("Sparkfun COM-18356 Test"); // Send a test message
}

void loop() {
  if (Serial.available() > 0) {
    // Read incoming data from the serial port
    char receivedChar = Serial.read();
    // Echo the received data back to the sender
    Serial.print("Received: ");
    Serial.println(receivedChar);
  }
}

1. Module Not Recognized by Computer:

   • Ensure the CH340C driver is installed. Download the driver from the Sparkfun website or the manufacturer's site.
   • Try using a different USB Type-C cable or port.

2. No Data Transmission:

   • Verify the TXD and RXD connections. Ensure they are not swapped.
   • Check the baud rate settings in your serial terminal program. The baud rate must match the device's configuration.

3. Device Not Powering On:

   • Confirm that the voltage jumper is set correctly (3.3V or 5V).
   • Ensure the USB cable is providing power.

4. Intermittent Communication Errors:

   • Use a shorter or higher-quality USB cable.
   • Check for loose connections or damaged wires.

Q: Can I use the COM-18356 with a Raspberry Pi?
A: Yes, the COM-18356 can be used with a Raspberry Pi. Connect the TXD, RXD, and GND pins to the corresponding GPIO pins on the Raspberry Pi. Ensure the voltage levels are compatible.

Q: What is the maximum baud rate supported by the COM-18356?
A: The COM-18356 supports baud rates up to 2 Mbps.

Q: Is the COM-18356 compatible with macOS Ventura?
A: Yes, the COM-18356 is compatible with macOS Ventura, provided the CH340C driver is installed.

Q: Can I power my microcontroller using the COM-18356?
A: Yes, the VCC pin can provide 3.3V or 5V power to your microcontroller, depending on the jumper configuration. Ensure the current requirements of your microcontroller do not exceed the module's capabilities.